Questions tagged [image-processing]

In general, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame.

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Image processing for eye movements

I have series of images extracted from a eye tracker video for both eyes. is there any image processing algorithm/method/technique available to find the following from those images: Horizontal eye ...
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1answer
239 views

Image watermarking in wavelet domain (data hiding in images)

I am working and researching on Image watermarking/steganography and I'm stuck at a point and want to know which technique is better in image processing for data hiding. Bit Plane Complexity ...
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238 views

Is it possible to reconstruct the original image from Laplacian pyramid?

In our computer vision course, my professor said we can reconstruct the original image from the Laplacian pyramid. It just feels to me that information is lost after doing subsampling and upsampling. ...
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70 views

Brightness equalization between different images

I am dealing with a proprietary whole slide image format from 3DHistech, namely MRXS. This image is produced by scanning a glass slide biopsy. The scanner takes pictures at certain positions which ...
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Image Processing- ornament detection

So I am working on a project where we are supposed to detect and count the red and gold ornaments in the picture provided in the link below. I am having issues detecting and counting each ornament and ...
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1answer
1k views

Region growing algorithm

I have been trying to come up with a region growing algorithm but I'm not sure that I fully understood the region growing segmentation method (for gray-scale images). Please correct me if I'm wrong: ...
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29 views

Producing masks from mostly-static-background subtraction when given the background

My data set contains a number of high resolution greyscale images containing a person's face. A single image containing the background without the face is provided. The background is mostly static in ...
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3answers
684 views

How to select the specific frame with object

I am detecting the object from the live camera through feature detection with svm , and it read every frame from camera while predicting which affect its speed , i just want that it should select the ...
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1answer
52 views

Isotropic and Anisotropic in the Total Variation Framework

The isotropic TV is defined as the estimation of 2-norm of gradients $\sqrt{(y_{i+1,j}-y_{i,j})^2+(y_{i,j+1}-y_{i,j})^2}$, while the anisotropic TV is defined as the estimation of 1-norm of gradients $...
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250 views

Image zooming with Fourier transform

I want to go from this image into this one: So basically I need to scale the white square. The authors of the paper claim that this can be done in four steps: zero-padding in real space (image is ...
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Concept of scales in Gabor filter

I've been reading about Gabor filters, and there is a concept of scale. While I understand that Gabor features help in analyzing both the frequency and orientations of an image, what is the idea of ...
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1answer
234 views

compression algorithm

Steganography can hide one image inside another. If we have a compression algorithm that allows us to fit the bits for two images into the size of one, can we think of a way to modify a run-length ...
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884 views

What are the various techniques for detecting Walls in the Building(Architectural) floor plan Images?

I have to process building floor plan images to extract Walls from the structure. It is trivial in case of binary images; but the images in our case are colored, and each have different color of walls....
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confused in difference between calculations of convolution and multiplication?

How are two signals multiplied? And how is it different from convolving two signals?? I have read the above question on dsp stack exchange and i also tried it in my matlab , code is as follow: ...
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568 views

How to get the scale bar of an FFT for a 2d image

I've been analyzing some images from a transmission electron microscope, including their FFTs, and I'm not sure how to apply a scale bar to the FFT images. I have calibrations for the real space image,...
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1answer
893 views

What is the Difference between Texture and Image?

I am beginner in the image processing I want to know what is difference between Texture and Image? or whether they are same? can anyone explain it. Also,if i want to do texture segmentation,can i ...
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1answer
37 views

Crop all written letters from single image

Above image has handwritten hindi / deavanagari letters all on a single image. Task is to Prepare a dataset from the given assignment.jpg image using image processing tools Idon't have clarity ...
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1answer
250 views

Haralick features, am I approaching this correctly?

I'm trying to personalise a custom CBIR by adding more features not only based on colour, but based on textures' features. What I don't know is if I'm approaching this well with Haralick's features. ...
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Segmentation of warped text lines

I am trying to segment warped text lines found in photos taken from a page of a book (from the camera of a smartphone). This is meant as a preprocessing step before running OCR on them. I have found ...
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2answers
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Binarization of image for varying background and foreground colors for OCR

I am trying to develop an automated OCR system for images obtained from the internet. The images mostly consist of computer generated text imposed on a background, so the OCR should produce near ...
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1answer
88 views

What do we mean by spectrum?

Consider the context of image processing and computer vision, and, in particular, discrete Fourier transform. For example, in the sentence In the Discrete Time Fourier Transform the forward ...
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Satellite imagery color normalization

Satellite images available from public sources (Google Maps, Bing, ArcGis, etc) have a common "flaw" with color balance abruptly changing in places where two different images were stitched (perhaps ...
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40 views

Sampling Theorem for images

A medical Image has a size of 8x8 inches. The sampling resolution is 5 cycles/mm. How many pixels are required? Will an image of size 256x256 be enough? I know sampling in 1D signal but cannot get ...
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How to perform a Stockwell Transform on a 2D matrix

I was looking at performing a Stockwell transform on a matrix (or an image as it has two directions - the matrix I am interested in has a spatial dimension and a time dimension, but this should make ...
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1answer
49 views

What does this notation $g(x) = S\{\delta(t) \}(x)$ mean?

What does this notation mean $g(x) = S\{\delta(t) \}(x)$ mean, where $S$ is a "system", $\delta(t)$ is the impulse function and $g(x)$ the output function of the system? I am really not familiar with ...
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203 views

Image Segmentation - Comparing GrabCut Method vs. Level Set Method

Checking the literature about image segmentation, if I am not wrong, there are two main approaches: Variational approach e.g. level-set optimization in Chan-Vese Combinatorial approach e.g. using ...
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27 views

Automatically crop out certain region around red objects

I have the image seen below and I would like be able to automatically crop out everything around each red section - not enough to overlap but enough that you can see how connected to the green parts ...
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2answers
430 views

Segment highly packed nuclei with dotted high intensity signal inside each object

I collected high magnification images on cell nuclei and I need to segment them (red circle in the image). The edges of the nuclei are visible but inside each nuclear object there are bright spots of ...
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1answer
383 views

How to Select Point Spread Function Empirically for Image Deconvolution?

When the captured image is blurring, one way of obtaining a clear image is via image deconvolution technique. In order to perform deconvolution successfully, usually we need to pay attention to the ...
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1answer
44 views

Difference Between Contrast Enhancement and Texture Enhancement in Images

I have a very basic question. I understand that contrast enhancement is exaggerating the difference between the intensity of the adjacent structures and texture in an image is the repeating geometric ...
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1answer
28 views

Encoding YUV Color Space with Positive Numbers

I got 2 hdr rgb textures/signals. When fetched one gets bicubicly interpolated and the other bilinearly. So I was thinking I can store as YUV and store Y from each texture in the bicubic one and the ...
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1answer
31 views

How to Remove the Patch Artifacts of Neural Network Denoising Process?

I have written a python script which uses the Noise2Noise: Learning Image Restoration without Clean Data implementation of the Auto Encoder which is useful to remove noise from images. In the original ...
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1answer
2k views

Ridge finding in noisy 2D image

I'm using MATLAB, and have experience with it but not with this kind of problem. I'm trying to identify white lines in noisy 2D images such as the one below. I can separate the brighter ones just by ...
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1answer
294 views

How to Validate Bilateral Filter Implementation?

For this may be a X-Y question, I'm providing the full background story: I'm trying to test for the correctness for a fixed point implementation of bilateral filter written in C. My current approach ...
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1answer
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Improving Canny Edge Detection and Contours Image Segmentation

I am working on an image segmentation project to identify playing cards on varying backgrounds. For my use case I care most that I accurately extract all the cards in the image; false-positives are ...
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1answer
344 views

SSIM(YUV) vs SSIM(Y): values very different

I'm seeing some weird results when trying to compare image qualities in a few different color spaces. Have a look at my graph: I want to compare with another publication, which reported PSNR(YUV) and ...
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2answers
19k views

Python - Normalized cross-correlation to measure similarites in 2 images

I'm trying to measure per-pixel similarities in two images (same array shape and type) using Python. In many scientific papers (like this one), normalized cross-correlation is used. Here's an image ...
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1answer
57 views

How Does Mean Centering Affect the Result of Using SVD to Compress Images?

I have been learning about using the Singular Value Decomposition to find low rank approximations to matrices. I had an image which I converted to a matrix. I regarded each row of the matrix as a '...
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1answer
269 views

Binarization, and then thinning/skeletonization

I have pictures of networks, like the one below, and my goal is to obtain the network's skeleton from processing those images. My approach lies in two steps, first I convert grayscale image to binary ...
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1answer
41 views

How to recognize for small video sequence with a large sequence?

I'm working on the idea of recognizing a small video sequence (a sequence of 18 seconds) within a long one (a sequence of 15 minutes), the first idea that come to mind stats that I have to ...
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2answers
74 views

Image Interpolation Using the Yule Walker Equations

I have been studying about the Yule-Walker equations for prediction of a time series data from knowledge of past values of the series. Is there any way I can use the same in an image to exploit the ...
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0answers
28 views

Understanding performance of Lucas Kanade Iterative Image Registration Technique

I am reading the paper: Lucas, B. D., & Kanade, T. (1981). An iterative image registration technique with an application to stereo vision. I am having some trouble understanding section 4.3 ...
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1answer
58 views

What Is a Weighted Local Histogram?

I'm reading through a couple of academic papers, and this terms often comes up "local weighted histogram". An example of quote is the following: First, cumulative histograms are built for every ...
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1answer
144 views

Homography Matrix Correlations

If the homography matrix of Image 1 to Image 2 is given, and another homography matrix for image 2 to image 3 is given, how do I calculate the homography matrix for image 1 to image 3? PS : I need the ...
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1answer
5k views

Differences between low-pass, band-pass, notch filters

I'm studying image processing and I know that there are different filters you can apply. I don't understand the difference between the low-pass/bandpass/notch filter (or high-pass/band-reject/notch). ...
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433 views

How to use the Walsh-Hadamard transform to filter 24 bit RGB color values in a localized spatial region?

After reading this Signal processing Stack Exchange article tonight, What is the Walsh-Hadamard Transform and what is it good for?, I became interested in applying the Walsh-Hadamard transform to ...
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1answer
248 views

Detect quasi-parallel lines with spurs in a binary image

I'm looking for a way to remove quasi-parallel curves from the net, as depicted in the figure. Not only the original nets (upper row in figure) contain many spurs, but also the curves to be detected ...
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2answers
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What does the “smoothing optical flow” mean?

I have this algorithm for Correlation Based Pyramids of images: • Create two Gaussian pyramids from the two input images • Compute optical flow using “5×5” regions on smallest pyramid level. • ...
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1answer
78 views

What motion estimation techniques that could estimate the motion of every pixel?

I'm trying to estimate a motion from a video, however based on my finding, those methods usually meant for large motion and sparse in nature. Optical flow: Sparse and fail to detect sub-pixel motion ...
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368 views

Deconvolution Question on Article “Deriving Intrinsic Images from Image Sequences” by Yair Weiss

there are n derivative filters: $f_i$, and denote $f_i^r$ as $f_i$'s reverse filter such that $$f_i(x,y)=f_i^r(-x, -y)$$ $r_i, f_i$ given, to find $r$ from the equations: $$f_i * r = r_i, (1 \leq i \...